Finishing sheet materials



Nov. 23, 1965 w. J. BENNES 3,213,751

FINISHING SHEET MATERIALS Filed June 26, 1963 5 Sheets-Sheet l 3 Sheets-Sheet 2 Filed June 26, 1963 NOV. 23, 1965 w, J, BENNES 3,218,761

FINISHING SHEET MATERIALS Filed June 26, 1963 5 Sheets-Sheet 3 0 3b 79 V 20 X 35 7g Til. S 1

35 76 i .E. W

United States Patent 3,218,761 FINISHING SHEET MATERIALS William J. Bennes, Union, N.J., assignor to Celanese Corporation of America, New York, N.Y., a corporation of Delaware Filed June 26, 1963, Ser. No. 2%,695 12 Claims. (Ci. 5187) The present invention relates broadly to the bufiing art, and is more particularly concerned with a novel method and apparatus for removing surface irregularities in plastic sheeting, featuring a substantially automatic finishing operation effective upon the entire surface area of a wide range of sheet thicknesses.

It is known that many plastic sheet materials, exemplified herein by cellulose acetate, require a finishing operation to effect removal of scratches and other surface irregularities. Surprisingly, while many technological advances have been made in most aspects of plastic sheet formation, even today the buifing of such sheets is essentially a hand operation. More specifically, it is the present practice for an operator to locate the sheet upon a supporting board of generally the same surface area as the sheet, to then advance the board with sheet thereon upon a roller which also provides a fulcrum, and for the operator to then exert a downward force upon one end of the board to cause the sheet thereon to abradingly contact a rotating bufiing roll.

As may be anticipated, the quality of work obtained depends in large part upon the operators experience and/or technique, and may further vary in direct proportion to the workers fatigue, so that as the end of the work day approaches, the rejection rate may be relatively high. In any event, it is not unusual in the art to re-process for a second bufiing operation approximately 30% of pro duction.

Many attempts have been made in the past to develop a machine which might overcome the disadvantages of the manual bufiing procedure. However, to date such endeavors have met with only partial success. To amplify, a continuous pass procedure resembling that employed in the metal working arts has been tried using for example three pairs of spaced feed rolls and two pairs of interposed buff rolls. However, it was found that if sheets of a thickness of the order of about 40 mils were warped, they would get caught as they entered the first pair of buff rolls or when leaving the second pair, resulting in chipping and/or burning. Lighter gauge materials, on the other hand, similarly became caught, causing edge curling and fractures.

The continuous pass machine suffers from another drawback in that clamping means are required to draw the sheets through the apparatus and guide means are needed for thinner gauge material. The latter means were noted to mar the sheets, often rendering them unacceptable, while the former means made it impossible to buff the entire surface area of the sheets.

It is accordingly an important object of the present invention to provide bufling method and apparatus featuring essentially automatic operation and the finishing to optical smoothness of the entire surface area of a wide range of sheet thicknesses.

Another object of the instant invention is to provide a buifing procedure wherein a sheet is advanced with one end forwardly into polishing contact with a pair of 'bufiing surfaces until a predetermined length of the sheet has been bufied, the advancement of the sheet being limited, the bufiing surfaces being moved out of contact with the sheet, and the opposite end of the sheet being advanced into polishing contact with the buffing surfaces so that the entire length of the sheet is polished on opposite surfaces thereof.

Still another object of this invention lies in the provision of a process for surface finishing plastic sheets wherein a sheet is advanced in a forward direction between a pair of rotatable bufiing surfaces to finish a predetermined length of the sheet on opposite surfaces thereof, the sheet then being preferably moved in a re verse .direction between the buffing surfaces without abrading contact therewith, and the sheet next being translated to feed the remaining length of the sheet forwardly through the bufiing surfaces in abrading contact therewith.

A further object of the present invention is to provide an apparatus for bufiing sheet materials in which the workpiece is advanced therethrough at a uniform speed, assuring that all portions of the workpiece will be polished to the same degree.

An even further object of the invention lies in the provision of abrading apparatus of the foregoing character wherein there is additionally included means to adjust the pressure applied by the bufling surfaces to the sheets and means for automatically applying bufiing compound to said surfaces.

Other objects and advantages of the present invention will become more apparent during the course of the following description, particularly when taken in connection with the accompanying drawings.

In the drawings, wherein like numerals are employed to designate like parts throughout the same:

FIGURE 1 is a top plan View of an illustrative form of apparatus, portions thereof being broken away to more clearly illustrate certain details:

FIGURE 2 is a side elevational view of the same apparatus with certain parts thereof being broken away to aid in the description; and

FIGURES 3 to 6 are diagrammatic views showing the action of the feed rolls, buff rolls, and buffing compound applicators during various portions of the abrading cycle.

Referring now first to FIGURES 1 and 2 of the drawings, there is provided in accordance with the principles of this invention bufiing apparatus generally designated by the legend A, and which comprises first and second enclosure means 10 and 11 equipped with suitable access openings mounting door means or the like 12. The first enclosure means 10 is formed by opposed side walls 13 and 1 and a connecting end wall 15 which cooperatively support a top wall 16 mounting a plurality of upstanding guide means 17 so located as to contact at least one marginal side portion of sheet or workpiece S to properly position it for entry into the operative structure contained within the second enclosure means 11. The first enclosure means 10 provides a loading station L, and desirably the top wall 16 is suitably covered by a soft lint-free material 18 to prevent scratching of the sheet S. The sheet is of uniform thickness throughout, and illustratively is formed of cellulose acetate. Typically, sheets processed by this invention may be approximately 21" by 50", and can vary in thickness between 20 and 250 mils while still being effectively buffed.

The second enclosure means 11 interiorly thereof houses a feeding or work moving station F and a buffing or polishing station B. The feeding station is comprised of a pair of vertically aligned feed rolls 19 and 20 constructed of or suitably covered by an elastomeric material. The feed rolls are journaled in bearing structure (not shown) which are carried in any desired manner by supporting components of the second enclosure means, and as appears in the views, shaft means 21 on the lower feed roll 26 mounts a pulley 22 over which is trained a belt 23 wrapping a pulley 24 supported by a shaft 25 on a reversing motor means M1. Of course, a chain and sprockets can be substituted for the belt and pulleys. Any desired mount may be provided for the motor M-l,

such as bracket means 26 connected to wall structure of the second enclosure means 11. The feed rolls I9 and 2t) normally counter-rotate in nip-defining relation in the direction of the arrows applied thereto, however, as will shortly be described, the named rolls preferably reverse their direction under control of motor means M-l to withdraw the sheet S when the buffing action has been partially and also wholly completed.

The sheet S makes entry into the pass between the feed rolls l9 and 2t) during movement from the loading station L by provision of a transverse opening 27 defined by inwardly directed portions 28a and 29a of wall members 28 and 29 of the second enclosure means 11. The wall portion 29a also cooperates with shield means 3% to reduce the amount of dusty removed sheet material and bufling compound which may enter the surrounding work area and the region of the motor means M1. In this same connection, there is also desirably provided dust removal means 31 extending transversely at the entry to the opening 27. Such means may take the form of a perforated pipe mounted by the wall member 28 and suitably connected to a blower so as to direct dust and other particles into the second enclosure 11 which is vented by an exhaust system shortly to be described.

The bufling station B is comprised of a pair of vertically aligned closely spaced buff rolls 35 and 36, the active body portions of which desirably are provided by unbleached muslin preferably taking the form of transversely abutting discs. The rolls 35 and 36 are supported upon shaft means 37 and 38 rotatably and swingably carried at one end by a pair of link members 39 and A and at their opposite ends by a pair of link members 41, only one of which can be seen. Each link member 39 and 40 includes a collar portion 39a and 40a loosely encircling one end of the shafts 37 and 38, as well as a collar portion 39b and 40b fixed as at 42 to one end of a pair of rod members 43 and 44- journaled for rotation at opposite ends in uprights 45 suitably supported by frame structure. In a like manner, the link members 41 at the opposite ends of the shafts 37 and 38 include a loosely encircling collar 41a and a collar 41b pinned or otherwise fixed as at 42 to the transversely extending rod members 43 and 44.

At one end of the rods 43 and 44, which is that end seen in the uppermost portion of FIGURE 1, the linkage system is completed by a pair of link arms 46 and 47, each of which includes a collar such as collar 46a and pinned as at 42 to the rod members 43 and 44 and a bifurcated portion 46b and 4712. In any event, to hold the rod 48 in a position of fixed adjustment removable pins 49 are passed through the ends 46b-47b and adjusting rod 48.

The adjusting rod is provided to control the extent of gap between the buff rolls to accommodate sheets of different thicknesses whereby said sheets can conveniently pass in a rearward direction between the buff rolls when said rolls are fluid actuated to an open position upon completion of a partial pass of the sheet therethrough. The adjusting rod terminates in a piston 50 which reciprocates within a stationary actuating cylinder 51 provided with fluid ports 52 and 53 leading thereinto. It is believed now manifest that upon removal of the pins 49 connecting the rod 48 to the ends of the link arms 46 and 47, and by rotating the rod through handle means 480, the relative position of the piston within the cylinder is controlled and thereby the gap between the buff rolls when actuated to an open position.

The buff rolls 35 and 36 are rotatively driven in an essentially identical manner by provision of motor means M2 and M-3, each of which mounts shaft means 55 carrying pulley means 56 over which is trained belt means 57 wrapping pulley means 58 mounted by the shaft means 37 and 38 of the buff rolls 35 and 36, respectively. Illustratively, the buff rolls may each be driven by a 7 /2 HP. 440 v. motor to impart thereto a peripheral speed of 3500 ft. per minute at 1800 r.p.m. The feed rolls 19 and 20, on the other hand, are driven at 45 r.p.m., and

with each roll having a diameter of 2 /2 inches, the peripheral speed thereof is about 30 ft. per minute.

Positioned immediately downstream from the buff rolls 35 and 36, and suitably connected to supporting structure, is a work receiving table 60. In generally this same location is a plurality of transversely spaced guide wires 61 connected at one end to the rod member 43 by screws of the like 62 and at their opposite ends to a transversely extending bar member 63, which may be equipped with tightenable collar members 64 to assure that the guide wires will at all times be taut. It may be noted from FIGURE 2 that when viewed in side elevation the wires slope downwardly from the rod 43 to the bar 63 so as to provide with the table a generally wedge-shaped tunnel. This facilitates direction of relatively light gauge sheet materials to switch means 66, the function of which will now be described.

The switch means 66, which desirably is of the pneumatic type known to the art, is suitably connected to a fluid source and is in control of valve means 67 through a conduit 68. The valve has a supply conduit 69 and a pair of discharge conduits 70 and 71 connected respectively to the ports 52 and 53 of the cylinder 51, which in turn controls the opening and closing of the buff rolls 35 and 36. It is also to be noted that the valve means 67 is equipped with a pair of electrical connections 72 and 73 leading to switch means 74 in control of the reversing action of motor means M-1 driving the feed rolls 19 and 20.

While a more complete description of the operation of the buffing apparatus will be given in connection with FIGURES 3 to 6, it may be here noted that after a predetermined length of the plastic sheet S (approximately one-half) has passed between the buff rolls 35 and 36 and has been thereby polished on opposite surfaces thereof, the leading end of the sheet passes into the switch means 66, interrupting the air flow thereto. This action actuates the valve means 67 selectively porting fluid through either of the conduits 70 or 71 to either of the inlets 52 or 53 of the cylinder 51, causing the buff rolls 35 and 36 to separate or open. In timed sequence there after the valve means 67 through electrical connections 72 and 73 and switch means 74 actuates the reversing mechanism in motor means M-1 to first stop and then reverse the rotation of the feed rolls 19 and 20, causing the sheet S to be withdrawn or moved rearward out of the bufling station B. The operator then translates the sheet 180 and introduces the unbuffed portion into the feed rolls.

To complete the description of the apparatus, there is also contained in the second enclosure means 11 a blower 76 under control of motor means M-4 for removing from the apparatus the abraded dust or particles. Also forming a part of the bufling apparatus herein provided is a pair of angularly disposed buffing compound applicators 78 and 79 suitably mounted by frame structure for controlled reciprocation. The applicators are of conventional construction, and can be hydraulically or pneumatically reciprocated under control of timer means 80 into contact with each of the buff rolls 35 and 36 to rub or deposit thereon compound from bars or blocks retained by the applicator structure.

With reference now also to FIGURES 3 to 6, the process concept of this invention is practiced by locating a sheet S to be polished in the loading station L with a marginal side edge thereof in abutment with the guide blocks 17. The sheet is moved forwardly by hand or other means until the leading'edge thereof is grasped by the nip-defining rubber feed rolls 19 and 20, which are at this time counter-rotating in the directions indicated by the arrows applied thereon. The sheet is advanced by the feed rolls to between the buff rolls 35 and 36 which are essentially closed and in pressure applying relation under control of the cylinder 51.

When approximately one-half of the length of the sheet S has passed between the buff rolls, the leading edge of the sheet activates the air switch 66, which in turn actuates the valve 67 to port fluid through one of the conduits 70 or 71 to one of the cylinder inlets 52 or 53 to cause opening of the buff rolls 35 and 36, the extent of the separation or gap being controlled by the adjusting rod 48. At this stage of the cycle, which is shown in FIGURE 4, the feed rolls 19 and are still rotating in a feed-in direction.

However, actuation of the valve 67 is also effective in programmed sequence to trip switch 74 which controls the reversing circuitry in motor means M4, first terminating rotation of the feed rolls and then reversing their rotational direction, as shown in FIGURE 5. At this stage, and in timed relation, the but]? rolls are beginning to close so that when the sheet S is completely withdrawn through the enclosure opening 27, the buff rolls are in their operating position.

The timer means 80 controlling the compound applicators 78 and 79 now causes them to advance into contacting relation with the buffs (FIGURE 6) to apply compound thereto, although it will be appreciated that this may not be required in each cycle.

The feed rolls 19 and 20 are now programmed by timer means controlling the switch 74 to again reverse, returning to their original or feed-in rotational direction. The operator, or mechanical means provided for this purpose, then translates the sheet S 180 and advances the unbufied end portion into the feed rolls to initiate a repetition of the cycle just described.

It is believed now apparent that applicant has provided a novel process and apparatus for buifing sheet materials which eliminates the earlier stated disadvantages of both the hand technique and the attempted continuous pass machine. While other features are present in the invention, one important aspect thereof is supporting the sheet at both ends thereof continuously throughout its travel. Thus, viewing FIGURE 2, it will be noted that as the leading end of the sheet enters the feed rolls 19 and 20, the trailing end is supported by the table top wall 16. Similarly, upon entry between the butt rolls 35 and 36 the sheet is also supported by the feed rolls, and for a portion of its travel by the top wall 16. In like manner, the leading end of the sheet receives support by the table 60 while rearward support is provided by the bufi rolls. It may thus be seen that by so proceeding there is no likelihood of damage to the sheet, as occurred in the attempted continuous pass machine. It is manifest that the modifications discussed herein as well as other changes can be effected without departing from the novel concepts of this invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are define-d as follows:

1. A method of finishing sheet materials, which comprises introducing a sheet between means providing a pair of nip-defining counter-rotating surfaces to advance said sheet between and into polishing contact with means defining a pair of bufiing surfaces, limiting the extent of travel of said sheet between said buffing surfaces so that only a predetermined length of said sheet passes therethrough and is polished, and in response to said limiting action, moving said bulfing surfaces out of polishing contact with said sheet and reversing the rotational direction of said counter-rotating surfaces to withdraw said sheet therefrom.

2. A method of finishing sheet materials, which comprises advancing a sheet by means providing a pair of nip-defining counter-rotating surfaces in a first direction into polishing contact with means defining a plurality of buffing surfaces, limiting the extent of travel of said sheet in contact with said buffing surfaces so that only a predetermined length of said sheet is polished thereby, and in response to said limiting action, reversing the rotational direction of said counter-rotating surfaces to move said sheet in an opposite direction.

3. A method of finishing sheet materials, which com prises advancing a sheet in a forward direction between and into polishing contact with means providing a pair of counter-rotating buffing surfaces, limiting the extent of travel of said sheet between said butting surfaces so that only a predetermined length of said sheet passes therethrough and is polished, and in response to said limiting action, moving said bufling surfaces out of polish ing contact with said sheet and moving said sheet in a reverse direction away from said bufiing surfaces.

4. A finishing method as defined in claim 1, in which subsequent to the steps claimed the unpolished portion of said sheet is introduced first into said nip and the claimed steps are repeated so that the total surface area of said sheet is polished.

5. A method of treating sheet materials, which comprises introducing a sheet between means providing a pair of nip-defining counter-rotating surfaces to advance said sheet between means defining a plurality of treating surfaces, limiting the extent of travel of said sheet between said treating surfaces so that only a predeter mined length of said sheet passes therethrouigh and is treated, and in response to said limiting action, moving said treating surfaces away from said sheet and reversing the rotational direction of said counter-rotating surfaces to withdraw said sheet therefrom.

6. A method of finishing sheet materials, which comprises directing a sheet forwardly between and in contact with means providing successive pairs of counterrotating surfaces, one pair of which performs a driving function and another a bufiing function, sensing the ex tent of forward travel of said sheet, and in response to said sensing action and while said sheet is contacted by said driving and buffing surfaces, rapidly and in timed sequence removing said bufling surfaces from contact with said sheet, reversing the direction of rotation of said surfaces performing said driving function to withdraw said sheet from between said bufiing surfaces, returning said bufling surfaces to a position for contact with said sheet, and again reversing the direction of rotation of said driving surfaces after said sheet has passed rearward- 1y therethrough.

7. A method of finishing a thermoplastic sheet, which comprises advancing the sheet with one end forward between and into polishing contact with means providing a pair of buffing surfaces, limiting the extent of travel of said sheet in contact with said bufiing surfaces so that only a predetermined length of said sheet in contact therewith is polished, moving said bufling surfaces out of polishing contact with said sheet when said predetermined length has passed in such buffing contact, and then advancing said sheet with its opposite end forward between and in polishing contact with means defining a pair of bufiing surfaces.

8. Apparatus for finishing sheet materials, comprising means for directing a sheet along a linear path of travel, drive means connected to said directing means for controlling the direction of travel of said sheet, buffing means along the path of travel of said sheet for polishing the surfaces thereof, means for moving said buffing means into and out of the path of travel of said sheet, and control means connected to said drive means and to said moving means and operable when said sheet has been directed a predetermined distance along said path of travel to move said buffing means out of said path of travel and to reverse the direction of linear movement of said sheet therealong.

9. Apparatus for finishing sheet materials, comprising roller means for directing a sheet along a linear path of travel, drive means connected to said roller means for controlling the direction of travel of said sheet, rotatable buffing means along the path of travel of said sheet for polishing the surfaces thereof, means for swinging said bulfing means into and out of the path of travel of said sheet, and control means connected to said drive means and to said swinging means and operable when said sheet has been directed a predetermined distance along said path of travel to move said bufling means out of said path of travel and to reverse the direction of linear movement of said sheet therealong.

10. Apparatus for finishing sheet material, comprising a pair of nip-defining counter-rotating rollers for direct ing a sheet along a linear path of travel, a pair of buifing rolls located for receiving therebetween said sheet from said rollers, means for driving said rollers in a sheetadvancing and a sheet-withdrawing direction, means for moving said buffing rolls into and out of polishing contact with said sheet, and sensing means positioned downstream of said buffing rolls in the path of travel of said sheet and operable when said sheet has moved a predeter mined distance along its path of travel to actuate said driving means and said moving means to move said buffing rolls out of polishing contact with said sheet and to drive said rollers in a sheet-withdrawing direction.

11. Finishing apparatus of the character defined in claim 10, in which the sensing means is pneumatic, and

in which guide means are provided to direct the sheet into the roller nip and also to the sensing means.

12. Apparatus for finishing sheet materials, comprising table means, a pair of rotatable buffing members, r0- tating means for advancing a sheet from said table means to introduce one end thereof between and into polishing contact with the buffing members, means connected to said buffing members for limiting the extent of travel of said sheet so that only a predetermined length thereof is polished and for separating said bufiing members to permit withdrawal of said sheet therefrom, and said limiting means being connected to said rotating means to reverse the rotation thereof and to effect the withdrawal of said sheet from said butting members.

References Qited by the Examiner UNITED STATES PATENTS LESTER M. SWINGLE, Primary Examiner. 

8. APPARATUS FOR FINISHING SHEET MATERIALS, COMPRISING MEANS FOR DIRECTING A SHEET ALONG A LINEAR PATH OF TRAVEL, DRIVE MEANS CONNECTED TO SAID DIRECTING MEANS FOR CONTROLLING THE DIRECTION OF TRAVEL OF SAID SHEET, BUFFING MEANS ALONG THE PATH OF TRAVEL OF SAID SHEET FOR POLISHING THE SURFACES THEREOF, MEANS FOR MOVING SAID BUFFING MEANS INTO AND OUT OF THE PATH OF TRAVEL OF SAID SHEET, AND CONTROL MEANS CONNECTED TO SAID DRIVE MEANS AND TO SAID MOVING 